The tobacco bins of the type with which the present invention is concerned are fairly deep, more or less rectangular in cross-section, and provided with an endless belt or plate type carrying conveyor which makes up the bottom of the bin. The carrying conveyor is designed to move tobacco in the bin to the bin exit end where the relatively deep, slowly moving tobacco load is separated by a discharge picker system which causes the tobacco to discharge in a more or less uniform manner onto a more shallowly loaded, quickly moving conveyor.
Customarily, the bin is filled by an endless so-called "shuttle" conveyor which is mounted on a moveable carriage positioned above the bin and able to traverse the length and width of the bin to fill the bin with tobacco. The shuttle conveyor, in turn, is fed by a feed conveyor positioned so as to deposit tobacco on the shuttle conveyor. Depending upon location of the bin in the tobacco processing plant, the bin may be used either for blending or bulking.
Normally, there are two parts to tobacco processing; the first part being leaf processing, where the tobacco leaves which have been flue or air cured, and received from local or foreign markets, are first moistened to facilitate handling, separated into good and bad leaves, and then subjected to threshing to remove stems, to grading and, finally, screening. At this point, the tobacco is subjected to drying, reordering and packed into barrels or boxes. Between the threshing and drying steps, the plants, by way of example, may have a plurality of storage and/or surge bins, to handle several streams from the threshing process for consolidation into one stream through the drying and reordering unit. In this instance, the bins function as bulking bins.
The tobacco may remain packed in barrels or boxes for several years before being removed and further processed. In this further primary processing, the tobacco is first subjected to multiple successive blending steps, depending upon the recipe of the final product. Two common types of tobacco are air cured burley and flue cured bright. There are also flavored or straight burley tobaccos, oriental tobacco, and others, and various grades of the same. In the multiple blending steps, a plurality of bins similar to the above storage or surge bins, and feed conveyors for the same, are used to accomplish the blending, the actual blending being carried out generally by laying the different types or grades of tobacco in layers in the bin, one on top of the other. Prior U.S. Pat. No. 2,827,058 to Bogaty, dated Mar. 18, 1958, assigned to assignee of the present application, shows such a primary processing plant layout.
Although, basically, a bulking bin and a blending bin have the same overall mechanical configuration, filling the bin, depending upon whether the purpose is storage or blending, can be different. A basic difference is that, in bulking, the filling starts across the width of the bin at a starting point in the bin, for instance one end of the bin, or the center of the bin, and then proceeds in one direction or the other (towards either end,) depositing tobacco to the top or a given level of the bin. This is carried out by directing the tobacco stream relatively quickly back and forth across the width of the bin with incremental movement of the shuttle belt in said direction (toward either end) until the bin or a portion thereof is filled. By contrast, in blending, as indicated above, a relatively thin layer extending full width and, typically, full or half length in the bin is first made with one grade or type of tobacco, and then a next layer is made with another grade or type, and so on, until the bin is filled.
There are also hybrid forms of blending and bulking. For instance, a plant could be on three shifts a day, and half of the bin may be blend filled to the top in the first shift, followed by blend filling the remainder of the bin to the top in the second shift. This permits the bin to be discharged through all three shifts, since the filling takes place at a more rapid rate than the discharge. Thus, the bin would be used, in a sense, for both blending and bulking.
With regard to the specific design of the bin, the shuttle conveyor which traverses the length of the bin can be as wide as the bin, or narrower than the bin. With the use of a shuttle conveyor as wide as the bin, it is then necessary to provide a feed conveyor capable of laying a wide strip on the shuttle conveyor or capable of reciprocating, thereby laying a narrow strip down at different widthwise locations on the shuttle conveyor. An example of this apparatus is shown in prior U.S. Pat. Nos. 3,735,881 to Wilding, dated May 29, 1973 and 3,811,585, also to Wilding, dated May 21, 1974.
With the use of a fairly narrow shuttle conveyor, narrower than the width of the bin, it is necessary to provide a means for causing the shuttle conveyor to move widthwise as well as lengthwise. An example of this type of apparatus is shown in a Sacket U.S. Pat. No. 3,435,967, dated Apr. 1, 1969. It should be noted that the Sackett patent is not concerned with filling tobacco bins, but it does show a shuttle conveyor capable of both widthwise and lengthwise movement across the top of a rectangular shaped bin.
The present invention constitutes an improved apparatus of this latter type, particularly useful for filling tobacco bins.
In the Sackett apparatus, the shuttle conveyor is mounted on a first pair of trucks which in turn move longitudinally in an X-direction above the bin on longitudinally extending tracks. These tracks, in turn, are mounted on a second pair of trucks which are capable of lateral Y-movement widthwise with respect to the bin. The primary movement of the shuttle conveyor is widthwise back and forth, interrupted periodically for longitudinal, incremental shifting of the conveyor to a next filling position.
In order to feed the shuttle conveyor, the apparatus of Sackett is provided with a bridge-shaped conveyor at right angles to the shuttle conveyor, and supported by the truck system on which the shuttle conveyor rides. This bridge conveyor is centrally located with regard to the path of travel of the shuttle conveyor so that material from the bridge conveyor automatically falls on the shuttle conveyor regardless of its position on the track system. The bridge conveyor, in turn, is fed by a delivery conveyor, all making a relatively complex, heavy or cumbersome system that has to be moved back and forth with each traverse. It should be emphasized that in the Sackett patent the bins are relatively small in size and are filled with a dense granular material which may be comparatively heavy. Thus, the rate of traverse of the feeding mechanism is relatively slow and the weight or inertia in the mechanism is as a result of little consequence.
However, in the present invention, the tobacco is relatively light weight, and the bins are by comparison very large, requiring rapid traverse, in either an X or Y direction. Thus the weight of the conveyor system which has to be moved with each traverse becomes important; particularly for rapid shuttle movement necessary in modern tobacco processing plant, to lay down many thin layers of tobacco necessary for improved consistency of a blend.
Accordingly, it is a principal object of the preent invention to provide a light-weight shuttle apparatus capable of rapid, reciprocal movement in either a longitudinal X or lateral Y direction and capable of laying relatively light-weight materials, such as tobacco, into a bin in the form of many thin layers. It is also an object of the present invention to provide a means for feeding the rapidly moving shuttle conveyor, which is capable of moving with the shuttle conveyor but which does not add to the weight or inertia of the conveyor.
In addition to the above, the prior art includes Mortland U.S. Pat. No. 3,125,231, dated Mar. 17, 1964; Quester U.S. Pat. No. 3,528,538, dated Sept. 15, 1970; Quester U.S. Pat. No. 3,532,207 dated Oct. 6, 1970; Allen U.S. Pat. No. 3,780,886 dated Dec. 25, 1973; and Burgess U.S. Pat. No. 3,877,585, dated Apr. 15, 1975.
None of the above patents suggest the concepts which constitute the present invention. The Allen patent shows a pivoting, narrow feed conveyor adapted to spread tobacco back and forth across a follow-up conveyor which, in turn, deposits the tobacco in a bin. However, the follow-up conveyor is of the same width as the bin, and for this and other reasons, the Allen patent is not an anticipation.